Why is a square both a rhombus and a rectangle?

A square is a rectangle. A square is a rectangle with equal sides. A rectangle Has to have 4 right angles (and only 4 corners). A Square has the same definition (4 right angles, and only 4 corners) but all the sides have to be equal.

A square is not a rhombus. A rhombus is a parallelogram with equal sides. A parallelogram has to have 4 sides (2 pairs of equal sides.) The equal sides must be parallel. A rhombus has the same definition (4 sides - 2 pairs of equal sides. The equal sides must be parallel.) but all the sides have to be equal lengths.